# SIP Calculator for Nepal Investors

> Project a recurring NEPSE purchase with monthly, quarterly, half-yearly or yearly contributions.

https://laganisaathi.com/calculators/sip.md

## Formula

Contributions are modelled as an **annuity due**, that is, made at the *start* of
each period:

```
periods_per_year = 1 (yearly) | 2 (half-yearly) | 4 (quarterly) | 12 (monthly)
n = periods_per_year × years
r = (annual return ÷ 100) ÷ periods_per_year
future value = payment × (((1 + r)^n − 1) ÷ r) × (1 + r)
```

The trailing `(1 + r)` is what makes it an annuity due. An end-of-period model
gives a slightly lower figure.

## Worked example

Rs 10,000 monthly for 10 years at 12% expected annual return:

- n = 12 × 10 = 120 payments, so Rs 12,00,000 invested
- **Future value = Rs 23,23,390.76**
- Gain = Rs 11,23,390.76, which is 93.62% of everything invested

## Caveat

This is a projection, not a forecast. It assumes a constant return, no fees and
no slippage. The NEPSE has years with negative returns, so the same rate applied
over a long period is rarely achieved in practice.